The size, shape and weight of rotor blades are factors that contribute to the energy efficiency of wind turbines. An increase in the rotor blade size increases the energy production of a wind turbine, while a decrease in weight also furthers the efficiency of a wind turbine. Furthermore, as rotor blade sizes grow, extra attention needs to be given to the structural integrity of the rotor blades.
In recent years wind turbines have grown significantly in size and the outer shape of the rotor blades has changed to a complex structure. Not only the thickness and the width change from the hub end to the tip end and from the leading edge to the trailing edge. The blade may also be pre-bent, angled, and/or twisted.
In order to facilitate transport of such large blades it is envisaged that the blades are made from a plurality of blade segments, which are assembled at the erection site of the wind turbine. There is a need in the art to ship the rotor blade in segments and then join the segments at the location of the wind turbine. It is not only a problem to transport the large rotor blades to the erection site; also the suspension of these large rotor blades is a problem.
A segment divided rotor blade comprises a plurality of blade segments such as two, three, four, five, six or any other number. A segment divided rotor blade typically comprises one hub blade segment, one tip blade segment and between zero and a plurality of intermediate blade segments.
Segment divided rotor blades furthermore have the advantage that the tip segment of a rotor blade can be replaced.
Wind farms are often situated in remote landscapes, on hill-tops or offshore locations; that is, locations that can be difficult to access. Heavy cranes can cause substantial damage to the ground and access roads. Offshore installation is often using a jack-up rig, a type of a mobile platform crane that is able to stand still on the sea floor resting on a number of supporting legs.
Large cranes and jack-up rigs are inherently costly, and difficult to transport, deploy, operate and demobilise. In addition, they can only be deployed in low-level wind conditions.
The geometry and the vulnerability of the blades make it difficult to position and assemble the blade segments and it is necessary to use several cranes, and different techniques for handling ropes, wire etc.